Wiring schematic

  • 145,000 MILES

The problem at the moment is malfunctioning brake lights. I need an electrical schematic, preferably free. I need one for the complete electrical system because I am also having other problems: windows will not work, replaced stereo does not go off when ignition is turned off, cruise control quits working until system is reset by disconnecting battery cables, etc. Can you send me one or let me know where to I can get one?

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Sunday, March 5th, 2017 AT 3:24 PM

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There are many dozens of pages of wiring diagrams. Your best bet is to get a paper copy of the manufacturer's service manual. Next, if you go to the top of this page and click on "Repair Guides", go to the lower right corner of that page and click on the "Mitchel" link, that will take you to the same site most independent repair shops use. Instead of spending over $1,000.00 per year, you can buy a subscription for just your vehicle. Cost is around $46.00 for five years, and less for one year.

Do you still hear the click of the turn signals? If you do not, put the original radio back in. Starting with some 2002 truck models, the engineers at GM cleverly built the Body Computer into the radio so you cannot replace it when it develops a problem. You are tied to the dealer and their two grossly-over-priced repair centers. To combat that, the aftermarket industry has come up with "radio relocation kits" that allow you to mount the original radio under the seat to keep the chime, turn signal "click", and cruise control functions. You just cut the speaker wires and run them to the new radio.

Aftermarket radios have the same twelve volt memory circuit and twelve volt switched circuit that original radios had since the mid 1980's. It is likely your original radio did not have a switched twelve volts. Most now just have a single constant twelve volts feed, and the radio is turned on with a digital "turn-on" signal generated in some other computer. You need to connect the switched twelve volt wire on the new radio, (usually the red wire), to some other circuit that only turns on when the ignition switch is on.

Also, be aware most aftermarket radios have a blue or yellow wire marked "power antenna" or "amp". In some cases it is marked, "switched twelve volts". That misleads people into thinking it is the one that needs to be connected to the ignition switch, but in fact, it gets twelve volts on it when the ignition switch and the radio are turned on. It powers a power antenna and / or remote amp. If that is connected to a twelve volt supply, it will bypass the radio's power switch, and the radio will not turn off.

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Sunday, March 5th, 2017 AT 4:05 PM

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